Semi-orthogonality of 0-pentenyl and S-ethyl glycosides:: application for the oligosaccharide synthesis

Novel semi-orthogonal glycosylation strategy with the use of 0-pentenyl and thioglycosides has been developed. According to this technique both armed and disarmed thioglycosides can be selectively activated with MeOTf in the presence of either armed or disarmed 0-pentenyl glycosides. The applicability of this novel strategy for the synthesis of a trans-cis glycosylation pattern, not accessible via conventional armed-disarmed approach, has been demonstrated for the synthesis of a linear tetrasaccharide derivative. (C) 2002 Elsevier Science Ltd. All rights reserved.